![FMC Technologies Smith Meter microFlow.net Liquid Скачать руководство пользователя страница 6](http://html.mh-extra.com/html/fmc-technologies/smith-meter-microflow-net-liquid/smith-meter-microflow-net-liquid_manual_2312633006.webp)
Page 6 • MNFL003 ║ Issue/Rev. 0.1 (9/13)
microFlow.net Liquid Modbus Communications Manual
Introduction
1.2
Floating Point Endian Control
Floating-point numbers are not defined in the Modbus specification; there are nearly as
many variations of how it is supported as there are vendors. Most often, Modbus registers
are combined sequentially to make up an IEEE single precision or double precision floating
point number; this is the case in the microFlow.net Liquid. Two registers are needed for
single precision and four fordouble precision numbers. There are, however, several ways to
map floating point values to Modbus registers. To assure compatibility with off-the-shelf
drivers, three popular variations of byte ordering for floating point numbers are supported
(see system program code 727).
1.3
Communications Control Selections
This program code defines the level of control the associated communications port commands.
Poll and Program, and Host Control are valid with host communications options. XON/
XOFF is valid with printer options. Selections are as follows:
None
– No communications control on this port.
Poll & Program
– For use with demonstration/microMate ports. Allows full program
access but does not affect transaction control (acts like a standalone unit).
Host Control
– Full programming and prompting control. plus transaction control
(requiring authorization from host). Allows use of AU or AP (Authorize, Authorize to
Preset) or SB (Set Batch) to enter the preset remotely.
Xon/Xoff
– For printer ports only. Xon/Xoff flow control.
PTB-FX
– For printer ports only. Security level designed to support PTB compliant
printers.
PTB-LQ
– For printer ports only. Security level designed to support PTB compliant
printers.
Critical:
Comm port not configured for host communications.
Critical:
Comm port not configured for printer.
Note:
No entry if corresponding function = Not Used.
Help:
Select the degree of control for this communications port.
1.4
Configuring the microFlow.net Liquid for Modbus Communications Via
Serial Port
• Press <Enter> at the Ready screen to access the Main Menu
• From the Main Menu, select Program Mode Menu and press <Enter>
• Enter the Access Code when prompted and press <Enter>
• From the Program Mode, select Comm Directory and press <Enter>
• Select Comm Port Config and press <Enter>
• From the Comm Port Config menu, select the desired port
• From the chosen communications port, set up the following items:
Baud
Rate
– the rate at which the Modbus device is sending data.
Data
Parity
– typical or standard setting is 8/None.
Control
– can be Host Control, but standard is Poll and Program due to
access being granted at the microFlow.net Liquid to start/stop batches (refer
to Comm. Control Settings in previous section).
Timeout
– dependent on Modbus host polling rate and number of slave
devices in the loop.